A cadaver study comparing two approaches to perform a maxillary nerve block in the horse.
Authors: Bardell D, Iff I, Mosing M
Journal: Equine veterinary journal
Summary
# Editorial Summary Maxillary nerve blocks are commonly performed in equine practice for dental and upper jaw procedures, yet surprisingly little evidence has compared the accuracy of different injection techniques. Bardell and colleagues evaluated two anatomically distinct approaches using 59 injections of methylene blue dye into cadaver horse heads: an angulated technique directed rostromedially from the ventral zygomatic process, and a perpendicular approach inserted below the zygomatic process level with the temporal canthus. Both methods achieved identical success rates—32% full hits (complete nerve coverage), 49–50% partial hits, and 18–19% complete misses—with no statistically significant difference between them. A notable finding was that the perpendicular method contacted bone consistently, whereas the angulated approach made contact in only 8 of 31 attempts, suggesting potential variability in landmark identification with the latter technique. The study underscores that neither approach guarantees reliable nerve anaesthesia on the first attempt, reinforcing the importance of careful patient assessment, supplementary regional blocks, and strict aspiration protocols before injection to avoid inadvertent intravascular placement—a complication documented once with each method.
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Practical Takeaways
- •Both the angulated (ANG) and perpendicular (PER) approaches to maxillary nerve blocks are equivalent in accuracy, so choice can be based on individual preference and anatomical landmarks available
- •Success rate with either method is approximately 32% full hits plus 49-50% partial hits, meaning clinicians should expect variable coverage and potentially need supplemental blocks
- •Always aspirate before injecting to avoid inadvertent intravascular deposition into the deep facial vein
Key Findings
- •Method ANG achieved 32% full hits, 49% partial hits, and 19% misses (10/31, 15/31, 6/31 respectively)
- •Method PER achieved 32% full hits, 50% partial hits, and 18% misses (9/28, 14/28, 5/28 respectively)
- •No statistically significant difference in accuracy between the two maxillary nerve block approaches
- •Vascular placement (deep facial vein) occurred once with each method; aspiration should precede injection to avoid intravascular injection